Mulch paper



United States Patent 3,165,862 MUICH PAPER Rex'S. Harper, Mobile, and Curtis A. Gentry, Chickasaw,

Ala, assignors to international Paper Company, New

This invention relates to the formation of a non-woven fabric from wood pulp fibers. More particularly, it relates to the production of a new material, from wood pulp fibers and without the use of Water, for plant mulching.

It is known to use wood pulp fibers in, for instance, plant mulching and in such a manner that a non-woven fabric made of such fibers is laid down. See US. Patent No. 3,017,720, issued January 23, 1962, and copending US. application Serial No. 167,925, filed January 22, 1962. But, in such instances, large quantities of Water are employed and the laying down, which is done at the plant site, requires mixers, pumps, hoses, spray heads of a size, number, and complexity such that it is largelyinconceivable that any individual home owner or even country club manager can afford or will wish to encumber himself with them.

A way has now been found, however, forusing wood pulp fibers as a plant mulch and otherwise which is, literally, within the grasp of such individuals. It involves the formation by manufacturers of sheets or rolls of non-' woven groundwood or chemical, e.g.', sulfate or sulfite, wood pulp fibers in the absence of water and binding agents. andthe, if desired, manual placement of such sheets or blankets over fertilized -or; unfertilized grass, flower, or other seed beds by individuals, preparatory to a simple wetting down with a garden hose or the like tov 7 mercially available equipment. Then, the mat is substantially finished for use by the homeowner or'the like by subjection to pressure and, preferably, heat under," for I of the products-of such steps are clearly many. Backing example, standard calender rolls adapted to deliver about 300 to 2000 lbs. pressure per lineal inch and a surface temperature in the range of about 200 to 400 F. More specifically, and by way of example, baled, flash dried sulfate pulpwhich has, desirably, been dyed green both for aesthetic reasons'and as a deterrent to attack by birds and the like once it hasbeen put to its ultimate use a is delivered to a hammermill such as the commercially available pre-opene'r made by 'jCurlator Corporation.

There, the bales are broken up and the fibers are flufied. V

Next, the 'fiufied fibers Which'are about /4 inch or less '0 in length are conveyed by pneumatic or mechanical means, but without water or binding agents, to another Curlator machine, the -13 Special 'Rando-Feeder and Randocalled condenser for forming a precursor mat of fibers, a.

doctoring device for removing the precursor matfrom the condenser, a lickerin for'breaking up the precursor met 3,165,862 Patented Jan. 19, 1965 and assuring a more even fiber distribution in the subsequent re-matting, and a second condenser for forming the desired mat-and emerges as a-blanket or fabric having a thickness of from about /2 to 1 /2 inches. The blanket is then travelled to a calender stack wherein a patterned steel roll adapted to be heated and a felted or rubber roll are positioned to deliver a nip pressure of about 500 lbs. per lineal inch and a surface temperature of about 300 F. to the blanket. An embossing calender of 66 inch length which is made commercially by B. F. Perkins and Sons, Inc. has been used for this purpose and, with it, there have been produced blankets ranging indensity from 3.3

Thus far, the blankets of the present invention have.

been given even greater strength by compressing together several plies thereof at elevated pressures, e.g., 5000 lbs.

per lineal inch or by bubbling steam therethrough. Presumably, this could also be done by'adding binding agents during the ,mat formation and activating such agents at the pressure or calendering station. The uses sheets for resins and foams, insulation in drinking cups or structural panels, wrapping andpackaging materials, fiber I board, wall board,insulating board, and outdoor protective coverings for machines, building materials and fuels,

includingpaper and paperboard made on a' 'Fourdrinier machine and lumber, plywood, and veneers cannot be excluded at this time.

However, moreimmediately, it has already'been found that a blanket of the present invention made from sulfate wood pulp fibers ofMi inch'or less in-length and having a sults when employed as a plant mulch appears to disintegrate to form, a cellulosic fiber to soil particle bond. The intimate contact with the surface soil particles results, itis believed, in a porous mat which I allows youngseedlings from newly germinated plants to penetrate the cover. This is in sharp contrast to the situation where the cover stems from awet process in situ paper sheet formation and holds together as a membrane,-

so as to deny intimate association of cellulosic fiber and soil particle and fre e passage to seedlings. And, the end:

resul-t'is that, in, for instance, grass establishment, the blanket of the present invention yields thicker andmore uniform grass growth than any wet-formed product. What is claimedis:

1. A' process consisting essentially of forming 'flash dried wood pulp fibers selected from the group consisting of groundwood and chemical wood pulp fibers into a mat by suction means and embossing the mat at'a pressure in v the range of about 300 to 2,000 lbs. per lineal inch. 1 V 2. A process consisting essentially of forming flash dried sulfate wood pulp fibershaving a'length of about {A inch intoa mat by suction'meansand embossingthe mat at a pressure of about 500 lbs. per lineal inch and at a temperature of about 300 F. I

3. The process of claim 1 wherein the embossing is conducted at a temperature in the range of about 200 F. to 400 F.

4. A mulching product consisting essentially of an embossed blanket of flash dried Wood pulp fibers selected from the group consisting of-groundwood and chemical wood pulp fibers, the blanket having a density of about 200 to 400 lbs. per 1,000 square yards.

5. A mulching product consisting essentially of an embossed blanket of flash dried sulfate Wood pulp fibers having a length of about /4 inch, the blanket having a density about 3l0lbs. per 1,000 square yards.

References Cited by the Examiner UNITED STATES PATENTS Viersen l8-47.5 Bryant 479 Clapp 47--l Linzell 162206 X Linzell l847.5 Clark et a1 l9155 X Roberts et al. 19l56 LHornmedieu l9-l6 1 X ABRAHAM'G. STONE, Primary Examiner.

T. GRAHAM CRAVER, Examiner. 

4. A MULCHING PRODUCT CONSISTING ESSENTIALLY OF AN EMBOSSED BLANKET OF FLASH DRIED WOOD PULP FIBERS SELECTED FROM THE GROUP CONSISTING OF GROUNDWOOD AND CHEMICAL WOOD PULP FIBERS, THE BLANKET HAVING A DENSITY OF ABOUT 200 TO 400 LBS. PER 1,000 SQUARE YARDS. 